king of the hill vs observation wheel

king of the hill

noun
  • A children's game in which one player stands on top of a hill or other location atop an incline, and attempts to repel other players whose goal is to capture his position. 

  • The player in this game who stands atop the hill. 

  • A person who has achieved a measure of success and is considered to be a leader in his field. 

observation wheel

noun
  • Ferris wheel 

How often have the words king of the hill and observation wheel occurred in a corpus of books? (source: Google Ngram Viewer )